Question

Скрестили двух кроликов с серой шерстью. В F1 — 25% с черной шерстью, 50% — с серой и 25% с белой. Определите генотипы и объясните такое расщепление

Answer 1

Явление неполного доминирования.А-черные,а- белые,Аа-серые

Р Аа * Аа

G А а  А а

F1 25% АА-черные.50% Аа-серые, 25% аа-белые.

Генотипы обоих кроликов Аа.

Answer 2

Genotypes and Explanation of the Phenotypic Ratios in Crossbreeding Two Rabbits

When two rabbits with gray fur are crossed, the resulting offspring can exhibit different phenotypic ratios. In this case, the phenotypic ratios are as follows: 25% black fur, 50% gray fur, and 25% white fur. To determine the genotypes and explain this type of segregation, we need to understand the genetic basis of fur color in rabbits.

Rabbit fur color is determined by multiple genes, with each gene having different alleles that contribute to the final phenotype. In this scenario, we can assume that there are two genes involved in determining fur color, each with two alleles.

Let's represent the alleles for the first gene as A and a, and the alleles for the second gene as B and b. The dominant alleles (A and B) result in black fur, while the recessive alleles (a and b) result in gray fur. The gray fur allele is incompletely dominant over the black fur allele, meaning that rabbits with the genotype Aa or Bb will have gray fur.

Based on the given phenotypic ratios, we can deduce the genotypes of the parent rabbits. Let's assume that one parent rabbit has the genotype AaBb (gray fur) and the other parent rabbit has the genotype AABb (black fur).

When these two rabbits are crossed, the possible genotypes and phenotypes of the offspring can be determined using a Punnett square:

         |  Aa  |  AB
   ------|------|------
    AaBb | AABb | AABb
    AaBb | AaBb | AaBb

From the Punnett square, we can see that there are four possible genotypes for the offspring: AABb, AaBb, AABb, and AaBb.

- 25% of the offspring will have the genotype AABb, resulting in black fur. - 50% of the offspring will have the genotype AaBb, resulting in gray fur. - 25% of the offspring will have the genotype AABb, resulting in white fur.

Therefore, the observed phenotypic ratios of 25% black fur, 50% gray fur, and 25% white fur can be explained by the genotypes of the parent rabbits and the inheritance patterns of the fur color genes.

It's important to note that this explanation is based on the assumption of a simplified genetic model for fur color in rabbits. In reality, the genetics of fur color can be more complex, with multiple genes and alleles involved. Additionally, environmental factors can also influence fur color to some extent.

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